There are ways to passively cool a house without airco. People have been building cool houses in hot climates for centuries. It doesn't always work, true. Once it is hot 24/7 and you don't have a source of cold anywhere you need airco. But it does explain why people consider airco a luxury item when used for cooling and not when used for heating.

I'm not saying people are always right when considering cooling a luxury while considering heating a necessity, but there is a historical reason for that mindset.